Both ideas are correct here. Adding anti-freeze up to 50% mixture will raise the boiling point (to about 258 degrees, if you have a 14 pound cap and it is in good shape), but taking out all the anti-freeze will make the car run cooler (slightly) because pure water is a better heat transfer agent. HOWEVER: In any Imperial with the cooling system in such a marginal state that you have to worry about things like this, you need to clean it out, including the block (see IML archives for procedure). These cars were (OVER)-designed with a cooling system that tolerates years of abuse and accumulated crud, even in severe environments (like Texas), so if it is telling you there is a problem, it is in really, REALLY bad shape. Clean the poor thing out before you warp a head or worse! I did this when I first got my Gold 68, in 1987. Since then, I have been using it as the family trip car in the desert Southwest for 15 years, including going through Las Vegas on a Sunday afternoon in August, idling in very heavy bumper to bumper traffic down the full length of the "strip", with the outside temperature at 118 degrees, with 6 people in the car, with my wife still complaining that she was "too cold; please turn the AC to a higher temp", with the temp gauge at the low end of normal, as usual! Dick Benjamin ----- Original Message ----- From: <mopar2@xxxxxxxxxx> To: <mailing-list@xxxxxxxxxxxxxxxx> Sent: Saturday, April 20, 2002 1:07 PM Subject: Re: IML: coolant system, overheating? > actually, adding more antifreeze will raise the boiling point of the coolent & it > won't boil over so easily. The ideal ratio is about 50/50. > John > > dardal@xxxxxxxxxxxxxxx wrote: > > > A suggestion for potentially overheating car. I learned that from my 68 sedan, > > that due to rust in the cooling system, tends to run hot in the summer. Here > > is one of the things I learned. The antifreeze necessary in the winter to > > prevent freezing and corrosion is reducing the heat transfer effectiveness of > > the coolant. So, when summer comes, I reduce the concentration, and that helps > > the car stay a little cooler. Also, since I am too lazy to attempt to clean > > the block from rust (actually I have tried, but not as good as I could have, or > > as DB has suggested) I have done the following. I installed a motorcycle > > radiator behind the grill and a series of valves. In the summer, I turn off > > the heater valve (Autotemp obviously not working, [yet!]) and turn on the valve > > that deviates the heater flow through the auxiliary radiator. That keeps the > > temperature bellow 210 in the hottest summer day driving at high speed > > (surprisingly, my overheating problem was not at idle). > > > > D^2, 2x68's > >